It is recognized that compounds containing halogen are among those effective for imparting flame resistance to flammable substrates. In particular, many organic bromine compounds are known agents for compounding flame retardant plastics, especially in combination with an antimony synergist. Brominated organic compounds of various types display different strengths and weaknesses. For example, polybrominated aromatic compounds have good thermal stability but tend to discolor in light. In contrast, aliphatic bromine compounds have good light stability but only moderate thermal stability.
The requirements for a suitable flame retardant extend beyond the sole ability to impart flame resistance. A flame retardant suitable for plastics must be highly compatible with its base material not only under conditions of use but at the stage where the plastic material is being compounded.
The environment of temperature and shear forces present in modern plastic milling equipment render some flame retardant compounds unsuitable because of instability, volatility, or a tendency to remain separate from the base plastic during compounding. The result is often a nonhomogenous product with unacceptable flame retardant characteristics.
It is desirable to develop new flame retardant agents which are effective, stable and easily compounded into plastic base materials processed in conventional equipment.